Long-term anticonvulsants for the treatment of generalized tonic-clonic and cortical local seizures. And, in the emergency control of certain acute convulsive episodes, e.g., those associated with status epilepticus, cholera, eclampsia, meningitis, tetanus, and toxic reactions to strychnine or local anesthetics.
Barbiturate; Anticonvulsant
Phenobarbital, the longest-acting barbiturate, is used for its anticonvulsant and sedative-hypnotic properties in the management of all seizure disorders except absence (petit mal). Phenobarbital acts on GABAA receptors, increasing synaptic inhibition. This has the effect of elevating seizure threshold and reducing the spread of seizure activity from a seizure focus. Phenobarbital may also inhibit calcium channels, resulting in a decrease in excitatory transmitter release. The sedative-hypnotic effects of phenobarbital are likely the result of its effect on the polysynaptic midbrain reticular formation, which controls CNS arousal.
ORAL Sedation: Adult: 30-120 mglday in 2-3 divided doses. Child: 6 mg/kg/day or 180 mg/ m2/day divided in 3 equal doses. Hypnotic: Adult: 100-320 mg at bedtime. Do not admin for >2 wk for the treatment of insomnia. Preoperative sedation: Child: 1-3 mg/kg 1-1.5 hr before procedure. INTRAMUSCULAR Sedation: Adult: As sodium: 30-120 mgI day in 2-3 divided doses. Preoperative sedation: Adult: As sodium: 100-200 mg 1-1.5 hr before procedure. Child: As sodium: 16-100mg 1-1.5 hr before procedure. INTRA VENOUS Preoperative sedation: Child: As sodium: 1-3 mg/kg 1-1.5 hr before procedure. PAR ENTERAL Hypnotic: Adult: As sodium: 100-320 mg at bedtime via IM/lV/SC inj. Child: As sodium: 3-5 mg/kg at bedtime via lM/lV/SC inj. ORAL Partial seizures;Generalised tonic clonic seizures: Adult: 60-180 mg daily taken at night. Titrate dose according to patient’s needs to achieve adequate control of seizures. Plasma concentrations of 15-40 mcg/ml (65-170 micromol/l) are usually required. Child: 1 mth-1 2 yr: Initially, 1-1.5 mgI kg bid. Increase by 2 mg/kg daily, as required, to a maintenance dose of 2.5-4 mg/ kg once or bid. 12-18 yr: Initially, 60-180 mg bid. Maintenance: 60-180 mg once daily. INTRAMUSCULAR Emergency management of acute seizures: Adult: As sodium: 200 mg IM repeated after 6 hr it necessary. Child: As sodium: 15 mg/kg IM as a single dose. INTRAVENOUS Status epilepticus: Adult: Doses of 10 mg/ kg to a max of 1 g. Child: As sodium: Neonates & child up to 12 yr: Initially, 20 mg/ kg by slow IV inj then 2.5-5 mg/kg once or bid. 12-18 yr: Initially 20 mg/kg (max 1g) by slow IV inj then 300 mg bid. Generalised tonic-clonic seizures; Partial seizures: Child: As sodium: Neonates: Loading dose is 20 mg/kg by slow IV inj followed by 2.5-5 mg/kg once daily either by slow IV inj or oraily.
The concomitant use of Alcohol or other CNS depressants may produce additive CNS depressant effects.
Severe renal & hepatic disorders. Severe resp depression, dyspnoea or airway obstruction; porphyria. Pregnancy. Elderly or debilitated patients, children. Withdraw gradually. Impaired renal, hepatic & resp function. Patients w/ acute pain & depressive disorders. May impair ability to dnve or operate machinery. Lactation.
Bradycardia, hypotension, syncope; drowsiness, lethargy, CNS excitation or depression, impaired judgment, hangover effect, confusion, somnolence, agitation, hyperkinesia, ataxia, nervousness. headache, insomnia, nightmares, hallucinations, anxiety, dizziness; rash, exfoliative dermatitis; nausea, vomiting, constipation: agranulocytosis, thrombocytopenia. megaloblastic anaemia; pain at inj site, thrombophlebitis (IV): oliguria: laryngospasm, resp depression, apnoea (especially w/ rapid IV admin), hypoventilation. Stevens- Johnson syndrome.
This drug should be used during pregnancy only if the benefit outweighs the risk to the fetus. Not recommended while breastfeeding.
The toxic dose of barbiturates varies considerably. In general, an oral dose of 1 gram of most barbiturates produces serious poisoning in an adult. Death commonly occurs after 2 to 10 grams of ingested barbiturate. Acute overdosage with barbiturates is manifested by CNS and respiratory depression Treatment of overdosage is mainly supportive and immediate hospitalization is necessary.
Keep below 30°C temperature, away from light & moisture. Keep out of the reach of children.
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